Say you have a card in your spread(e.g arrow) and draw another (e.g balance)
If you cast both the same target the second cast will overwrite the first
Yes, even if they are different cards.
Not sure if the buff from two different AST can stack or work the same way.
Since i haven't done any serious content yet. I will admit that i use to get excited when i got the "dream". Arrow + Balance in my spread and draw then used time dilation. I feel really dumb now.